TABLE 1.

Salt compositions and their molar ratios in the treatment groups.

Treatment groups	NaCl	Na2SO4	NaHCO3	Na2CO3
A	1	1	0	0
B	1	2	1	0
C	2	8	9	1
D	1	1	1	1
E	8	2	2	8

A, pH 7.31–7.49; B, pH 8.48–8.59; C, pH 9.10–9.28; D, pH 10.07–10.19; E, pH 10.66–10.73.